Translating system



I July 5 1949 M. ARDl-rl ETAL 2,474,811

TRANSLATING SYS TEM Filed Dot@ 5, 1946 2 Sheets-Sheet 1 l AoRA/W- 31113'45 1949- M. ARDl'rl ETAL 2,474,811

TRANSLATING SYSTEM 2 sheets-sheet g Filed oct. I5, 1946 A 7 TORNEY Pctented Jill! l194|#v UNITED STATE TRANSLATING SYSTEM Maurice Arditi, New York, and Irwin H. Franzel and Joseph Feinstein, Brooklyn, N. Y., assigner! to Federal Telecommunication Laboratories, Inc., New York, N. Y., a corporation of Delaware Application October 5, 1916, Serial No. 701,438

15 Claims. 1

This invention relates generally to electrical translating systems and particularly to systems for translating amplitude varying energy into time modulated pulses.

Translating systems, particularly pulse timemodulation systems have been heretofore pro- -posed which utilize cathode ray tubes in the process of modulation as well as for the distributing of channels in a multi-channel time modulated pulse system. See for example, the co-pending application of E. Labin-D. D. Grieg, Serial No. 567,414, illed December 9, 1944. In such systems, the cathode ray tubes proposed are structurally relatively complex and require precision in manufacture. Moreover exact control is necessary for the beam sweep, beam configuration, and beam density.

An object of the present invention is the provi'- sion of an improved translating system.

Another object is the provision of an improved modulator for time modulated pulses characterized by the use of energy having recurrent slop- ,2 produce channel distribution and a single output train of time modulated pulses.

ing characteristics for producing the effective l modulation.

According to a feature of the present invention.

energy having a recurrent sloping characteristic is applied between a pair of electrodes of an electron discharge device at the same time that the signal energy is applied thereto. The instantaneous amplitude of the signal with relation to the portion of the sloping characteristic coincident therewith determines the output from said electrodes and determines when said output has a value over a given level. In terms of said level, therefore, the amplitudes of said signal and said sloping lcharacteristic have an effect that varies in time. lUse is made of this to produce time Y modulated pulses.

In accordance with another feature of the present invention use is made of a cathode ray tube having secondary emitting target elements and a collector. The primary electron beam is regularly interrupted to produce control pulses which are shaped to provide sloping characteristics. The secondary emission between the collector and the secondary emitting target elements is controlled by said controlled pulses and the channel signals to produce a modulation in time whereby the output derived from said collector elements varies in time according to the amplitude variation of the signal. A single common output is 'used for the target elements and since each of said elements responds to voltages derived from different signal channels, the corresponding Another object of the present invention is the provision of an improved pulse time modulator and channel mixer utilizing a cathode ray tube.

The above mentioned and other features and objects of this invention will become more apparent and the invention itself though not necessarily deiined by said features and objects will be best understood, by reference to the following description of an embodiment of the invention taken in connection with the accompanying drawings, wherein:

Fig. l is a schematic and block diagram of a modulator and channel mixer system employing a cathode ray tube;

Fig. 2 is a schematic and block diagram illustrating a modification of the system of Fig. 1; and

Fig. 3 is a set of curves used in describing the operation of the systems of Fig. 1.

Referring now to Fig. 1 the cathode ray tube I includes the usual envelope 2 having therewithin a cathode ray gun 3, deecting elements 4, an aperture plate 5 serving as a secondary emission collector, having apertures 6 through which the beam passes to strike target elements 'I, with one target element provided for each channel. The

beam is cyclically deflected by means of voltages derived from the sweep voltage generator 8 applied to the deflection plates l, the sweep generator 8 being in the present example adapted to produce two voltages of the same frequency out of phase with each other, which are separately applied to the horizontally and vertically deflecting plates respectively. The beam, therefore, travels in a circle past the aperture plate seq uentially passing through the apertures in said plate to sequentially impinge upon the target elements 'I which latter are likewise arranged in a, circle. The target elements 1 are secondary emission electrodes which upon being struckA by the primary electrons of the beam emit secondary electrons which, when the voltages applied to the collector electrode 5 are of suilicient value, cause a flow there-between. Separate signal sources 9, I0, I I etc. each forming part of a different signal channel are connected at o ne of their terminals yto separate ones of the target elements 1, and at their other ends to a sawtooth generator I2. The sawtooth generator I2 is in turn coupled in series with an output resistance I3 to the collector lelectrode I5. The output voltages appearing across output resistance I3 are fed to a diflerentiator and clipper I4 where the pulses are differentiated and then clipped. For proper operation it is desirable that the sawtooth generator I2 be synarmen chronized with the sweep voltage generator l as indicated by line I5.

The operation of the system of Fig. 1 may be best understood with reference to the curves of Fig. 3. As stated hereinbefore the beam from 5 the electron gun 3 (which is continuously on during operation) is rotated so as to sequentially strike the target elements 1. 'I'hese emit secondary electrons which go to the collector when the voltages are of suillcient and proper value thereby l causing an electron ow between a target element and the collector 5. Referring to curve .A the line I6 represents the characteristics o1' the current flow Ia of the secondary electrons from one of saidelements 1 to the collector 5 with 15 changes in voltage Ea applied to the collector 5. When the voltage applied to the collector is below a given level indicated by the broken line I1 no current will ilow. When however, the

voltage is above the level l1 the current arises 20 steeply as indicated by the line I6. The sawtooth generator I2 is so timed with respect to sweep voltage generator 8 that each time the beam strikes a target element there is applied between -said target element and said collector a sawtooth voltage I8 (see curve B). This sawtooth voltage is in series with the amplitude varying signal from one of the sources 9, I0, II, etc. A biasing voltage is normally applied from source I9 so that the signal voltage itself is insufficient` 30 to cause a secondary electron current flow. Thus, for example in curve B the signal level indicated by the broken line 20 is below the cutoff level I1. However, the coincidence of the signal and the sawtooth results in the passing of the cutoff level I1 during some part of the sloping portion of the sawtooth to thereby initiate the now of secondary electrons. The time of initiation of this ilow will vary depending solely upon the amplitude of the signal, since the sawtooth pulses are of constant amplitude. As for example, with the signal level at 2| (curve B) it Will be seen that the ilow will be later than it would be if the signal were at 2U, whereas with the signal level at 22 the flow is initiated earlier. terminated by either the end of the sawtooth pulse or it may be terminated by the beam being deflected away from a target element. In either case, since the deection is uniform and since the sawtooth pulses recur regularly the termination of said flow is always regular, and only the initiation thereof varies. Consequently, as indicated in curve C, pulses 23 through 25 are produced of variable width. These pulses are then differentiated as shown by curve D in the dil'l'erentiator 55 and clipper I4,and are thereafter clipped in device I 4 along the level 26 to produce pulses as shown in curve E which are time modulated in the sense that they are time displaced. It is to be noted that the term time modulation" is used herein, except when otherwise noted, in a broad sense so that the pulses 23 to 25 are also considered time modulated since they vary in their duration. Assuming that the signal levels 20, 2l and 22 are diilerent instantaneous levels 65 of signals from sources 9, I0 and I I respectively, it will be seen that the pulses 23, 24 and 25 each represent a diilerent channel and that these pulses are interleaved or mixed so as to form a singletrain as indiuated in curve E with the first pulse 21 being part of one channel, 28 being part of another channel and 29 being a part of a third channel.

While in the system of Fig. 1 a separate sawtooth generator is disclosed, in the system of Fig.-

The flow may be 45 2 the sawteeth are generated under the control of the cathode ray tube and particularly under the control of its deflection. This is accomplished in the system of Fig. 2 by providing a modified form oi.' cathode ray tube 30 which includes in addition to the elements of the cathode ray tube of Fig. 1 an additional aperture plate 3|. 'I'he aperture plate 3l is provided with apertures alined with those of aperture plate 5 and the beam passes through both plates to strike the target elements. When, however, the beam strikes between the apertures of plate 3| it strikes the solid portion of said aperture plate v3| and each time produces a. rectangular pulse 32. The pulse 32 is suitably shaped in a. shaper 33 to provide pulses having sloping characteristics, which may be for example. sawtooth pulses. These, after a suitable delay in delay device 34, are applied between the collector 5 and the target elements 1 in series with the dillerent signals from sources 9, I0 and While we have described above the principles of our invention in connection with specific apparatus and modications thereof, it is to be clearly understood that this description is made only by way of example and not as a limitation on the scope of our invention.

What we claim ist' 1. A translating system for varying energy comprising an electron discharge device having a secondary emissive electrode, an electron collector, means for directing electrons to said electrode to cause the emission of secondary electrons, means for producing energy having recurrent sloping characteristics, and means for applying both of said energies for controlling the flow of said secondary electrons from the electrode to the collector to vary the time during which the value of said flow exceeds a given level.

2. A translating system for varying energy comprising an electron discharge device having a secondary emission electrode, an electron collector, means for directing electrons to said electrode to cause the emission of secondary electrons, means for impressing energy'having recurrent sloping characteristics in series with the varying energy between said electrode and collector for controlling the ilow of said secondary electronsj from the electrode to the collector to vary the time during which the value of said ow exceeds a given level.

3. A translating system for amplitude varying energy comprising an electron discharge device having a secondary emissive electrode, an electron collector, means for directing electrons to said electrode to cause the emission of secondary electrons, means for normally biassing said collector with respect to said electrode to cut oil the flow of secondary electrons therebetween, means for producing energy having recurrent sloping characteristics, and means for applying both of said energies for controlling the now of said secondary electrons, the amplitude of said rst mentioned energy determining the time during which said ilow occurs.

4. A system for producing time modulated signals in response to varying amplitude signals comprising an electron discharge device having a secondary emissive electrode, an electron collector, meansl for directing electrons of said electrodes, to cause the 'emission of secondary electrons, means normally biasing said collector with respect to said electrode to cut oil the ow of secondary emission electrons therebetween, means for impressing energy having recurrent vsloping characteristics in series with the signals between said electrode and collector for intermittently causing the ilow of said secondary electrons from the electrons to collector to produce output pulses time modulated in accordance with the amplitude modulation of the input signals.

5. A system for vproducing time modulated pulses in response to varying amplitude signals from a plurality of different channels, and for mixing the pulses corresponding to the diierent channels to form a single chain of multi-channels time modulated pulses comprising a cathode ray tube having a' plurality of target elements, means for producing an electron beam, and means for cyclically deiiecting said beam to sequentially scan said target element, a common output for said target elements, means for producing energy having a recurrent sloping characteristic, and means for applying said energy and said signals to said target elements to control the output current therefrom to vary the time during which the value of said current exceeds a given level.

6. A system for producing time modulated pulses in responseto varying amplitude signals from a plurality of diil'erent channels, and for mixing the pulses corresponding to the diilerent channels to form a single train of multi-channel time modulated pulses comprising a cathode ray tube having a' plurality of secondary electron emitting target elements, means for producing an electron beam, and means for cyclically deilecting said beam to sequentially scan said target elements, a secondary electron collector, means for producing energy having a recurrent sloping characteristic, andvmeans for applying said energy and said signals for controlling the flow of said secondary electrons from said elements to the collector to vary the time during which the value oi.' said flow exceeds a given level.

7. In a system for producing time modulated vpulses in response to varying amplitude signals from a plurality oi' diilerent channels and for mixing the pulses corresponding to the dierent channels to form a single chain oi multi-channel time modulated pulses, an electron discharge device having electron emitting means and electron collecting means, means for sequentially switching different signal channels to control the electron-ilow between said emitting means and said collecting means, means i'or producing energy having a recurrent sloping characteristic, and

means for applying said energy to further control said electron ilow, the output being coupled to said collecting means.

8. In a system for producing time modulated pulses in response to varying amplitude signals from a plurality of .diilerent channels, and for mixing the pulses corresponding to the diirerent channels to form a single train of multi-channel time modulated pulses, an electron discharge device having electron emitting means and electron collecting means. means for sequentially and cyclically switching dilerent signal channels to control the electron ow between said emitting means and said collecting means, means for producing energy having a recurrent sloping characteristic, and means i'or applying said energy to further control said electron iiow.

9. In a system lor producing'time modulated pulses in response to varying amplitude signals from a plurality oi' diilerent channels, and for mixing the pulses corresponding to the diilerent channels -to form a slnle train of multi-channel time modulated pulses. sn electron discharge' respective ones of said elements in series with device having electron emitting means and electron collecting means, means for sequentially and cyclically switching different signal channels to control the electron owbetwen said to further control said electron iiow that a part l of the sloping -portion of said energy and a part of said signal substantially simultaneously control said low.

10.A system according to'claim 9 further including means for synchronizing said energy producing means with said switching means.

11. A system according to claim 9 further including means for synchronizing the switching means with said applying means so that said recurrent sloping characteristic of said energy occurs substantially simultaneously with the switching of a signal channel to control said electron flow.

12. A translating system for signals comprising an electron discharge device lhaving means for producing a flow of primary electrons, means for producing in response to said primary electron flow, a ow of secondary electrons, means for controlling one of said ows to produce energy having recurrent sloping characteristics, and means responsive -to said energy and said signals for controlling the other oi' said ows.

13. A translating system ior signals comprising a cathode ray tube including means for producing a beam of primary electrons, a secondary emissive target element, and a collector element, means for deiiecting said beam to strike said target element, means for controlling said beam to produce energy having'a recurrent sloping characteristic, and means for applying said energy on said signals to control the iiow of secondary electrons to vary the time during which the value of said low exceeds a given level.

14. A translating system according to claim 13 wherein said controlling means comprises a conductive electrode arranged in the path of said beam and adapted to interrupt said beam as the beam is being deiiected.

15. A multiplex time modulation system comprising a plurality of electronic target elements, means for applying a voltage having a recurrent sloping characteristic to each oi' said elements, means for applying individual signal voltages to said recurrent voltage, scanning means for scanning said elements sequentially rendering said elements eiective to produce electrical energy dependent upon the applied voltages, and a common output means for said produced energy.

. MAURICE ARDITI.

IRWIN H. FRANZEL. JOSEPH FEINSTEIN.

REFERENCES CITED The following references are ot record in the le of this patent:

UNITED STATES PATENTS Number Name A Date 2,026,892 Heintz Jan. '7, 1936 2,173,193 Zworykin Sept. 19, 1989 2,185,693 Mertz Jan. 2, 1940 2,189,315 Karolus Ileb. 6, 1940 2,250,528 Gray L July 29, 1941 2,257,795 Gray Oct. 7. 1941 2,265,216 Wolf Dec. 9, 1941 

